1CMP0023
2-------
3
4Plain and keyword :command:`target_link_libraries` signatures cannot be mixed.
5
6CMake 2.8.12 introduced the :command:`target_link_libraries` signature using
7the ``PUBLIC``, ``PRIVATE``, and ``INTERFACE`` keywords to generalize the
8``LINK_PUBLIC`` and ``LINK_PRIVATE`` keywords introduced in CMake 2.8.7.
9Use of signatures with any of these keywords sets the link interface of a
10target explicitly, even if empty.  This produces confusing behavior
11when used in combination with the historical behavior of the plain
12:command:`target_link_libraries` signature.  For example, consider the code:
13
14::
15
16 target_link_libraries(mylib A)
17 target_link_libraries(mylib PRIVATE B)
18
19After the first line the link interface has not been set explicitly so
20CMake would use the link implementation, A, as the link interface.
21However, the second line sets the link interface to empty.  In order
22to avoid this subtle behavior CMake now prefers to disallow mixing the
23plain and keyword signatures of :command:`target_link_libraries` for a single
24target.
25
26The ``OLD`` behavior for this policy is to allow keyword and plain
27:command:`target_link_libraries` signatures to be mixed.  The ``NEW`` behavior for
28this policy is to not to allow mixing of the keyword and plain
29signatures.
30
31This policy was introduced in CMake version 2.8.12.  CMake version
32|release| warns when the policy is not set and uses ``OLD`` behavior.  Use
33the :command:`cmake_policy` command to set it to ``OLD`` or ``NEW`` explicitly.
34
35.. include:: DEPRECATED.txt
36